The complexity of life took billions of years to push and stretch and reshape the biological niche that is Earth. It would seem prudent - if one had the means - to save some portion of the blueprints of this majesty, so that the process would not have to start over from scratch in the event of a global cataclysm.
Such apocalyptic thoughts spur scientists on to discover some way to preserve mankind, along with all terrestrial flora and fauna, in case the Earth's bell is rung suddenly. Nuclear war is not the only way the lights could go out for the human race Asteroid strikes, pandemics, climatological or geological catastrophes could also do humans in. So it makes sense for earthlings to have an insurance policy to guarantee their survival so it's no surprise that the European Space Agency should think aloud about building a whole DNA library on more...